Investigation of activity of monoterpenes and phenylpropanoids against immature stages of Amblyomma cajennense and Rhipicephalus sanguineus (Acari: Ixodidae)

Abstract

The objective of this study was to assess the acaricidal activity of carvacrol, thymol, eugenol, and (E)-cinnamaldehyde on unengorged larvae and nymphs of Amblyomma cajennense and Rhipicephalus sanguineus, using the modified larval packet test. Carvacrol, eugenol, and (E)-cinnamaldehyde were tested at concentrations of 2.5, 5.0, 10.0, 15.0, and 20.0 μl/ml, while thymol was tested at concentrations of 2.5, 5.0, 10.0, 15.0, and 20.0 mg/ml, in all cases with 10 repetitions per treatment. For the A. cajennense larvae, mortality rates caused by carvacrol, thymol, eugenol, and (E)-cinnamaldehyde at the lowest concentration were 45.0, 62.7, 10.2, and 81.6%, respectively, reached 100% at the concentration of 5.0 μl/ml for carvacrol and (E)-cinnamaldehyde and 5.0 mg/ml for thymol, while this mortality was observed at 15.0 μl/ml for eugenol. For the nymphs of this species, carvacrol and thymol caused 100% mortality starting at a concentration of 5.0 μl/ml and 10.0 mg/ml, respectively, while eugenol caused 100% mortality at 20.0 μl/ml and the mortality caused by (E)-cinnamaldehyde did not exceed 64%. In the tests with R. sanguineus larvae, the lowest concentration of carvacrol and (E)-cinnamaldehyde resulted in 100% mortality, while this percentage was observed starting at 10.0 μl/ml for eugenol. For nymphs, carvacrol and thymol at the smallest concentration caused 100% lethality, unlike the results for eugenol and (E)-cinnamaldehyde, where 100% mortality was only observed starting at the concentration of 10.0 μl/ml. The results obtained indicate that the tested substances have acaricidal activity on unengorged larvae and nymphs of A. cajennense and R. sanguineus.

Synergism of thymol, carvacrol and eugenol in larvae of the cattle tick,Rhipicephalus microplus, and brown dog tick,Rhipicephalus sanguineus

“…Previous investigations of the effects of eugenol (Monteiro et al , ), thymol (Scoralik et al , ) and carvacrol (Senra et al , ) alone against R. microplus have demonstrated high larval mortality (near or equal to 100%) starting from the lowest concentrations tested. The same was observed by Senra et al () with carvacrol and eugenol, and by Daemon et al () with thymol in R. sanguineus s.l. larvae.…”

“…concentrations tested. The same was observed by Senra et al (2013b) with carvacrol and eugenol, and by Daemon et al (2012) with thymol in R. sanguineus s.l. larvae.…”

“…The acaricidal effects of thymol, carvacrol and eugenol in R. microplus and R. sanguineus larvae have been demonstrated in previous studies Senra et al, 2013aSenra et al, , 2013b. Furthermore, Novato et al (2015) demonstrated that the association of carvacrol + thymol at certain concentrations had synergistic effects in A. sculptum and D. nitens larvae.…”

“…Its acaricidal activity has been confirmed against R. microplus , D. nitens (Monteiro et al , ), A. cajennense s.l. and R. sanguineus (Senra et al , ).…”

Potential role of ATP‐binding cassette transporters against acaricides in the brown dog tick Rhipicephalus sanguineus sensu lato

“…Susceptibility of larvae to FIP and IVM. The larval packet test (LPT) was used to investigate IVM and FIP lethal concentrations according to the FAO (1984), with some modifications to improve practicality without compromising efficiency (Fernandes et al, 2008;Senra et al, 2013). Specifically, each packet contained 20 larvae and was composed of filter paper measuring 2 × 4 cm (Labor 67 g/m 2 ; Tecnochimica Moderna Srl, Rome, Italy).…”